During the last months I have seen the following behavior on my workstation:- In normal operation, the IPv4 and IPv6 addresses of the opnsense box are passed as DNS servers to the workstation.- From time to time, the IPv6 addresses of the Google DNS servers are passed to the workstation as well, thus bypassing the resolution of the hostnames in the internal network configured in Unbound DNS Server overrides. This happens spontaneously, i.e. the workstation boots up in the desired state and spontaneously transitions into the undesired state.

When the issue is present, systemd-resolve --status on the workstation gives (shortened):

I just observed it happening again. IPv6 DNS servers from Settings | General | DNS servers are propagated. unbound has stopped working at 12:35:28 (last log entry) for no reason and does not come back to live. system.log shows the following: